1. Field
One or more embodiments of the following description relate to an apparatus and method for creating a ghost-free High Dynamic Range Image (HDRI) based on a filtering, that may obtain an effect as if a fixed camera captures consecutive images of a stationary object, when a moving camera continuously captures a scene with a moving object by varying an exposure.
2. Description of the Related Art
Most of technologies for creating a single High Dynamic Range Image (HDRI) using several Low Dynamic Range Images (LDRIs) acquired from a single scene by varying an exposure of a camera are based on an assumption that the scene is fixed.
However, since an object is typically moving in real-world environments, it is difficult to acquire several LDRIs from a single fixed scene.
A phenomenon where a single object appears several times in an HDRI may occur due to motions of the object. Such a phenomenon is referred to as a ghost phenomenon.
A scheme of preventing the ghost phenomenon may be broadly divided into two schemes.
A first scheme is performed to classify pixels of an LDRI into a background and a foreground, and to define a foreground area where motion exists as a ghost area.
A second scheme is performed to define a reference frame among several LDRIs, and to determine an area where a motion is determined to exist as a ghost area, based on the reference frame.
When the first scheme is used, an interesting object in motion may be incorrectly classified as a ghost, and removed. Accordingly, the second scheme may be more effective in practical aspect than the first scheme.
In conventional schemes of solving this ghosting problem based on a reference frame, a ghost area may be detected using appropriate schemes, the detected ghost area may be excluded, and a weighted sum of radiances of several exposures may be performed using the Debevec and Malik's method, set forth in 1997, so that a final radiance value may be determined and the HDRI created.
However, generally, it is difficult to exactly and accurately identify a ghost area. Additionally, when a ghost area is incorrectly identified, pixel value(s) corresponding to the actual ghost area may still be included in the combining of weighted values. Accordingly, an HDRI may still contain the undesired ghosting.